Initial Findings

The Volpe team started by looking at the daily VMT for all scenarios. This is done by combining seven DVMT outputs by location and type of mode.

## [1] "VERSPM_NVTA"
## [1] "VERSPM_NVTA_A2"
## [1] "VERSPM_NVTA_B2"
## [1] "VERSPM_NVTA_C2"
## [1] "VERSPM_NVTA_D2"
## [1] "VERSPM_NVTA_E2"
## [1] "VERSPM_NVTA_F2"
## [1] "VERSPM_NVTA_G2"
## [1] "VERSPM_NVTA_G3"
## [1] "VERSPM_NVTA_H2"
## [1] "VERSPM_NVTA_I2"
## [1] "VERSPM_NVTA_J2"
## [1] "VERSPM_NVTA_K2"
## [1] "VERSPM_NVTA_L2"
## [1] "VERSPM_NVTA_L3"
## [1] "VERSPM_NVTA_M2"
## [1] "VERSPM_NVTA_M3"
## [1] "VERSPM_NVTA_N2"
## [1] "VERSPM_NVTA_O2"
## [1] "VERSPM_NVTA_P2"

Validation

The Volpe team also realized the need to validate the VisionEval output.

MWCOG DVMT

The VDOT team sent along daily VMT values in 2021 and 2045 from the MWCOG MOE Base model. These results include household car VMT, business car VMT, and car travel from other locations (such as motorists who live outside the area and are passing through it.

Here are the raw results from the MWCOG base model in 2045:

Jurisdiction Freeway Expressway Major Art. Minor Art. Collector Ramp All
Fairfax County 12,517,806 5,910,760 6,219,736 1,419,677 1,256,563 488,882 27,813,424
City of Fairfax 0 284,867 99,406 9,144 0 0 393,417
Falls Church 0 106,172 40,693 4,605 0 0 151,470

CROSSTAB ROW=FLAG COL=FTYPE VAR=_24VMTTRK

Jurisdiction Freeway Expressway Major Art. Minor Art. Collector Ramp All
Fairfax County 3,071,425 988,206 919,784 212,966 331,425 90,603 5,614,408
City of Fairfax 0 37,640 12,957 774 0 0 51,371
Falls Church 0 18,944 5,575 425 0 0 24,944

When you add all of the numbers up, you get 34,049,034 daily VMTs. This is about 4,000,000 higher than the VisionEval dvmt values. The chart below shows the percent differences with each of our scenarios.

Here is a table showing some of the validation steps taken:

File from the Travel Demand Model Value Output from NOVA model Output from VisionEval (Base Model) Percent Difference
2019i4_Trip_Generation_Summary.txt HH DVMT 34,049,034 30,040,347 5-15%
2019i4_Trip_Generation_Summary.txt Truck DVMT 5,690,723 1,206,452 70-80%